Facial contour and geometry are being used to design masks and to identify mask usage in many medical fields including CPAP (Constant Positive Air Pressure). CPAP masks are used to provide a breathable mixture of gases, typically air, provided at above ambient pressure to a patient. A CPAP mask forms a seal around a nose and mouth of a patient's face, providing an interface between the air source and the patient's respiratory system that is ideally free of leaks. CPAP masks are used in a wide variety of medical treatment procedures including for instance the treatment of Obstructive Sleep Apnea (OSA). During such treatment, the patient wearing the mask inhales the pressurized air, which prevents tongue tissue from obstructing the air passages. Because of the use of pressurized air, the facial mask must provide a proper seal with the patient's face.
A CPAP mask typically comprises a cuff and a dome that is optionally supported by a forehead pad. The cuff forms a seal around the patient's face, whereas the dome sits over the patient's nose and mouth and provides a conduit to the source of air. Ideally, the seal is air-tight under the pressure in normal service. Typically, cuffs in CPAP masks comprise silicon gaskets, and other materials with similar properties of high elasticity.
Besides good sealing qualities, the facial mask should also feature proper fitting and comfort properties. However, CPAP masks often lead to irritations around the face of the patient. This is particularly found in medical environments, where the mask may be worn for hours or days without changing or removing from the face. This occurs because silicon gaskets often do not seal well to the patient's face, especially around the bridge and lower sides of the nose. The resulting air leaks into the patient's eyes, causing irritations. These air leaks can be avoided by pushing the CPAP mask more tightly to the patient's face. However, this pressure can lead to minor red marks or open sores. Additionally, individuals have widely varying sensitivities to mechanical pressure. A combination of skin and eye irritations reduces patient tolerance and compliance with the medical procedure utilizing the mask.
Obviously, the sizes and shapes of patient's faces differ from person to person. In order to maximize compliance for the CPAP therapy, the CPAP masks have to be customized and to be adjusted as well as possible to the patient's face. Therefore, personalized sizing information has to be captured from the patient's face for customizing the CPAP masks. Known sizing gauges are based on cut-outs in bags, plastic sliders, or templates on packaging that contacts the patient's face. However, the known sizing gauges cover a part of the patient's face and thereby obstruct the view of a clinician trying to fit the facial mask. This, in turn, will lead to an inaccurate fitting of the facial mask. Moreover, the current sizing gauges are not suitable for multi-patient use, because they need to be cleaned or disinfected after contacting the patient's face. Additionally, the known sizing gauges are extra components shipped with each mask and thereby create a lot of plastic waste. These problems also apply to other mask types or masks used for other applications, like BiPAP masks (Biphasic Positive Airway Pressure), masks for firefighters, military masks etc.